Phosphorus enrichment of streams and lakes in Central Texas is a severe environmental
problem, much of which originates, at specific key sites, from phosphorus
loads in dairy wastewater. In simple terms, the problem is that wastewater
from dairies is high in phosophorus levels. When applied to lands used for
irrigation of crops and pastures, this nutrient-rich wastewater poses a significant
non-point source pollution risk, especially during rainfall runoff events.
The problem is especially severe since phosphorus is thought to be one of
the main limiting factors that are responsible for algal growth and blooms
in surface waters. In contrast, if the phosophorus content of dairy effluents
were reduced significantly, the threats to water quality would likely diminish.

Recently, municipal and industrial wastewater treatment plants have reduced
phosphorus concentrations to minimal levels using precipitation by struvite,
an ammonium and magnesium phosphate [Mg-NH4-PO4]. In these applications, the
use of struvite also allows phosphorus in raw wastewater to be removed and
then reused as a source of fertilizer. In this project, samples of dairy lagoon
wastewater will be collected from privately-run dairies near Stephenville,
TX in the Bosque River watershed of Central Texas. A series of tests will
be conducted on subsamples taken from this wastewater. The ionic composition
and pH buffer capacity will be determined. Then, after laboratory analysis
has been conducted, tests will be run to determine the optimal way to use
struvite to treat wastewaters with varying levels of phosphorus, magnesium,
and nitrogen-related compounds.

The anticipated result from this project is that a methodology could be developed
that would remove significant levels of phosphorus from dairy wastewater,
while increasing the nitrogen content that could be recovered by treating
this effluent stream. The project would also determine how the recovered nitrogen
could be reused for the iririgation of various grasses. In sum, these effects
would lead to ways to improve water quality be removing potential sources
of nutrients and non-point pollutants.